neurosurgery

Networker

The neurosurgery doc says he did 61559 and the plastic doc did 21175. The report states the neurosurgery doc did bifrontal craniotomy and barrel-stave osteotomies. I am wondering:
1. Can 61557 be billed with 61559.
2. Is it ok for me to bill 61557,61559 (for neurosurgery doc) with 21175 (for plastic doc). The CPT book states that 21175 should be billed with 61557 (only?)